forwarders and another company's split dns

[srp336 at getcoactive.com]

We have a sister company which has a split dns. They have an external
server hosting their public dns records and also a private server on
their LAN which, among other things, is being dynamically updated by
Microsoft Active Directory. We'd like to be able to see those AD
entries in their private name server. We have unrestricted access
through a point-to-point T1 to that server.

Is it possible to set our copy of bind to forward queries to that
server as well as use the external name server for their domain (a
domain which we don't host here)?

Thanks!